Hello Iain,
I tried reproducing the described issue, but to no avail. You can find attached my sample project, implementing the described scenario. Please compare it with your actual project and check if there are differences in the setup or if I have misunderstood something in your scenario.
It is possible that the RadRating isn't shown because of custom style sheets that interfere with the correct display of the control. I would suggest verifying if there is CSS that hides the rating, included on your page.
Note that at the current circumstances I am mostly guessing as to what your setup is and if you are still unable to resolve your problems please provide a more detailed description of your setup so that we can suggest a specific answer.
All the best,
Slav
the Telerik team